The present invention relates generally to indoor communication cables and more specifically to glass fiber reinforced premises cables.
Fiberoptic cables are commonly used to provide electronic communication in a wide variety of indoor and outdoor communication systems. One type of indoor fiberoptic cables, typically referred to as premises, plenum, or riser cables, are comprised of buffered optical fibers and loose reinforcement polyaramid fibers contained within a fire resistant polymer jacket.
The polyaramid fibers are typically coated with a coating that prevents abraiding during fiber generation.
Polyaramid fibers have many important functions within premises cables. First, the polyaramid fibers provide some tensile strength during the installation process. Second, the polyaramid fibers act as a cushion and space filler to protect and suspend the loose fiberoptic fibers within the polymer jacket. Third, the polyaramid fibers prevent the adhesion of the fiberoptic fibers to the polymer jacket wall.
One problem with the use of polyaramid fibers in premises cable is that the aramid fiber may add additional fuel for fire and smoke generation in certain flammable situations. This is due to the fact that aramid fibers are organic fibers.
It is therefore highly desirable to provide a method for reducing or eliminating the possibility of fire or smoke generation in reinforcement fibers used in premises cables while maintaining the structural and protection attributes of the reinforcement fiber. It is also highly desirable that the reinforcement fibers used in premises cable do not ribbonize, or form bundles, that bend the fiberoptic fibers within the polymer jacket. This bending may lead to attenuation of the fiberoptic fibers, which can limit the ability of the fiber to transmit a light signal.
It is thus an object of the present invention to provide a method for reducing or eliminating the possibility of fire or smoke generation in reinforcement fibers used in premises cables while maintaining the structural and protection attributes of the reinforcement fibers used in indoor communication cables.
The above object is accomplished by replacing the polyaramid fibers typically found in premises cables with a sized glass reinforcement fiber. As the glass fibers are inorganic, not organic, these fibers would reduce the possibility of fire or smoke generation within the premises cable. This is especially beneficial for indoor communication cables such as a premises cable that are used in commercial or residential buildings.
In addition, the glass fibers provide similar structural and protection characteristics as compared with polyaramid fibers. First, the glass fibers provide some tensile strength during the installation process. Second, the glass fibers act as a cushion and space filler to protect and suspend the loose fiberoptic fibers within the polymer jacket, thereby minimizing attenuation of the fiberoptic fibers. Third, the glass fibers prevent the adhesion of the fiberoptic fibers to the polymer jacket wall. Fourth, as the glass fibers are non-ribbonized (individually sized strands, not bundle or bunched), they tend to provide uniform insulation throughout the interior of the premises cable and around the loose fiberoptic fibers. Fifth, installation of the glass fiber reinforced cable is preferred, as the polyaramid fibers do not cut as well using installation tooling.